CVE-2026-25766 | Echo has a Windows path traversal via backslash in middleware.Static default filesystem

Exp

Echo is a Go web framework. In versions 5.0.0 through 5.0.2 on Windows, Echo’s `middleware.Static` using the default filesystem allows path traversal via backslashes, enabling unauthenticated remote file read outside the static root. In `middleware/static.go`, the requested path is unescaped and normalized with `path.Clean` (URL semantics). `path.Clean` does not treat `\` as a path separator, so `..\` sequences remain in the cleaned path. The resulting path is then passed to `currentFS.Open(...)`. When the filesystem is left at the default (nil), Echo uses `defaultFS` which calls `os.Open` (`echo.go:792`). On Windows, `os.Open` treats `\` as a path separator and resolves `..\`, allowing traversal outside the static root. Version 5.0.3 fixes the issue.

Published: 2026-02-19 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-25766 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.33%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-25766

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-25766

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.07% 0.33% +0.26%
2 2026-04-02 0.05% 0.07% +0.02%
3 2026-02-20 — 0.05% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-25766

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 1.4 [email protected]

Weakness enumeration for CVE-2026-25766

GitHub Security Advisory for CVE-2026-25766

GHSA-pgvm-wxw2-hrv9 · Severity: medium · Ecosystem: go — Echo has a Windows path traversal via backslash in middleware.Static default filesystem

OS Trackers for CVE-2026-25766

vendor priority summary link
debian unimportant CVE-2026-25766 unimportant priority: Debian including 3 source packages (golang-github-labstack-echo, golang-github-labstack-echo.v2, golang-github-labstack-echo.v3), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. https://security-tracker.debian.org/tracker/CVE-2026-25766
ubuntu medium CVE-2026-25766 medium priority: Ubuntu including 3 source packages (golang-github-labstack-echo, golang-github-labstack-echo.v2, golang-github-labstack-echo.v3), 14 status rows across 5 suites (focal, jammy, noble, questing, upstream): not-affected 10, DNE 4. https://ubuntu.com/security/CVE-2026-25766

Affected software / configurations for CVE-2026-25766

Vendor Product Version Raw CPE
labstack echo >= 5.0.0, < 5.0.3 cpe:2.3:a:labstack:echo:*:*:*:*:*:go:*:*

References for CVE-2026-25766

cvelogic Threat Intelligence